In some medical procedures, energy is imparted to body tissue locally, in a concentrated dose, and it is desirable to cool the treatment area in order to reduce collateral tissue damage.
For example, cardiac ablation therapy is used to treat arrhythmias by heating tissue with radio-frequency (RF) electrical energy to create non-conducting lesions in the myocardium. It has been found that cooling the area of the ablation site reduces tissue charring and thrombus formation. For this purpose, Biosense Webster Inc. (Irvine, Calif.) offers the ThermoCool® irrigated-tip catheter as part of its integrated ablation system. The metal catheter tip, which is energized with RF current to ablate the tissue, has a number of peripheral holes, distributed circumferentially around the tip, for irrigation of the treatment site. A pump coupled to the catheter delivers saline solution to the catheter tip, and the solution flows out through the holes during the procedure in order to cool the catheter tip and the tissue.
Catheter tubes are prone to kinking, and a number of methods for avoiding kinks are known in the art. For example, U.S. Pat. No. 5,460,608 describes a balloon catheter having an outer shaft and an inner shaft in which the inner shaft is constructed to protect itself over its entire length, especially in its most vulnerable areas, while maintaining flexibility. The inner shaft can be reinforced to prevent it from collapsing or breaking throughout its length and also improving the deflation time of the balloon.